The control of bleeding as well as sealing of air and various bodily fluids is essential and critical in surgical procedures to minimize blood loss, to seal tissue and organ structures, to reduce post-surgical complications, and to shorten the duration of the surgery in the operating room.
In an effort to provide dressings with enhanced hemostatic and tissue sealing and adhering properties, therapeutic agents, including, but not limited to, thrombin, fibrin and fibrinogen have been combined with dressing carriers or substrates, including gelatin-based carriers, polysaccharide-based carriers, glycolic acid or lactic acid-based carriers and a collagen matrix. Examples of such dressings are disclosed in U.S. Pat. No. 6,762,336, U.S. Pat. No. 6,733,774 and PCT publication WO 2004/064878 A1.
Due to its biodegradability and its bactericidal, tissue sealing, tissue repairing, drug delivering and hemostatic properties, it is desirable to utilize cellulose that has been oxidized to contain carboxylic acid moieties, hereinafter referred to as carboxylic-oxidized cellulose, as a topical dressing in a variety of surgical procedures, including neurosurgery, abdominal surgery, cardiovascular surgery, thoracic surgery, head and neck surgery, pelvic surgery and skin and subcutaneous tissue procedures.
However, when carboxylic-oxidized cellulose is utilized in combination with thrombin and/or fibrinogen, the acidic moieties that may be present in the cellulose denature the activity of the thrombin and/or fibrinogen. Therefore, it is desirable to shield the and/or fibrinogen from such acid moieties to maintain their hemostatic activities.
As used herein, the term “nonwoven fabric” includes, but is not limited to, bonded fabrics, formed fabrics, or engineered fabrics, that are manufactured by processes other than, weaving or knitting. More specifically, the term “nonwoven fabric” refers to a porous, textile-like material, usually in flat sheet form, composed primarily or entirely of staple fibers assembled in a web, sheet or batt. The structure of the nonwoven fabric is based on the arrangement of, for example, staple fibers that are typically arranged more or less randomly. The tensile, stress-strain and tactile properties of the nonwoven fabric ordinarily stem from fiber to fiber friction created by entanglement and reinforcement of, for example, staple fibers, and/or from adhesive, chemical or physical bonding. Notwithstanding, the raw materials used to manufacture the nonwoven fabric may be yarns, scrims, netting, or filaments made by processes that include, weaving or knitting.